1. Field of the Invention
The present invention relates to a boot adapted to sports that require movement of the foot, such as snowshoeing, conventional or skating style cross country skiing, telemark skiing and hiking, and/or to gliding sports such as snowboarding, ice skating and roller skating, i.e., sports that require a good transmission of the forces exerted by the foot for a better grip and edge setting.
2. Background and Material Information
In all of the aforementioned sports, it is necessary to transmit the forces coming from the user's leg via the ankle, from the foot to the contact zone of the boot with the ground or a gliding support. During practice of any of the above-mentioned sports, the contact zone, which is localized in a so-called metatarsophalangeal zone, must remain constantly in contact with the support and/or the ground, even when the user lifts the heel of a foot to make a stride, and/or to displace the center of gravity with respect to the direction of the gliding support. As a result, the portion of the foot and of the boot located behind the metatarsophalangeal zone forms an angle with the portion of the boot located in front of such zone during the lifting. This angle translates into a bending of the user's foot, and therefore of the boot, in the metatarsophalangeal zone.
Therefore, it must be noted that a boot adapted to the aforementioned sports must first meet the requirement for sufficient flexibility in the metatarsophalangeal zone to allow as natural a movement as possible.
The transmission of the forces coming from the user's leg to the metatarsophalangeal zone, which represents the impulse zone of the foot with respect to the ground and/or support, constitutes the second requirement to be met by a boot intended for the aforementioned sports. To prevent a loss of forces due to shock absorption and parasitic deformation, it is necessary to stiffen the base structure of the boot.
In addition, it is important to avoid any movement of the foot with respect to the boot. This results, in particular, into the necessity of a satisfactory retention of the heel inside the boot.
To summarize, a boot adapted to the above-mentioned sports must meet various and incompatible requirements, which, at the outset, cannot be accomplished without being detrimental to at least one of the aforementioned aspects.
That is why numerous approaches have been attempted until now, intended to solve this problem. For example, it is known to provide a cross country ski boot with a substantially non-flexible sole. Of course, the resulting problem is that a natural movement of the foot is no longer achievable, since the sole resists the natural bending movement in the metatarsophalangeal zone.
Another approach known, for example, from the document IT 195 621, consists of the arrangement of an edge ascending from the external sole which surrounds the entire boot. However, this construction does not allow a natural movement of the foot.
Yet another approach known, for example, from the document EP-A-309 437, consists of the arrangement of a more or less flexible sole and of a flexible stiffener, which surrounds the heel. However, this construction allows neither a satisfactory heel retention, nor an efficient transmission of the forces coming from the user's leg.